(1) Field of the Invention
The present invention relates to a transverse-member motor-vehicle module for receiving the instrument panel and reinforcing the bodywork for the direct connection of the two A-pillars of a motor vehicle, composed of a transverse member with a steering-column retainer, where the transverse-member module, i.e. not only the transverse member but also the steering-column retainer, are manufactured using a metal-plastic-composite design (hybrid technology), and these are composed of at least one main body and of at least one thermoplastic part and one second thermoplastic part, where these have been securely bonded via injection moulding firstly to the main body and simultaneously the various plastics parts have been bonded to one another, where the two plastics parts are composed of different plastics materials and these are injected in the bi-injection moulding process, where they fuse with one another when they encounter one another and enter into a secure bond with the metal.
(2) Description of Related Art
Known steering-column retainers, also termed steering consoles, are composed of a plurality of welded sheet-metal profiles in steel or diecast components (e.g. composed of aluminium or magnesium), welded to the load-bearing structure of the instrument-panel transverse member to give transverse-member modules, or securely connected so as to form a single piece or, respectively, in the form of combined profiles, composed of aluminium, of steel, of magnesium, or of plastics-metal-hybrid design.
DE 10 2005 004 605 A1 discloses a transverse-member module for a motor vehicle comprising an at least partially plastics-surrounded metal tube, with, moulded on so as to form a single piece, a plastics duct through which a conductor set can be passed, with a moulded-on link composed of plastic, for fixing to the front wall of the motor vehicle by screw-thread methods.
DE 102 40 395 A1 discloses a transverse member which is intended for a motor vehicle and which, in the region of the curved portion of the tube, has a welded-on metal steering-column link, onto which the screw-on plate of the steering column is mounted. The manufacture of the curved section of the said transverse member uses a metal-plastics-hybrid design.
DE 200 08 201U1 discloses an instrument-panel support in hybrid-type configuration for installation between the A-pillars of a motor vehicle and having an elongate, shell-like main body, and also stabilizing insert parts composed of metallic materials, which have been joined via moulded-on interior plastics ribbing to give a metal/plastics-composite part, and through which at least one air duct passes at least to some extent, where, simultaneously with the plastics ribbing, retainers, consoles and link points composed of plastic and projecting outwards from the main body have been moulded on so as to give a single piece.
DE 100 64 522 A1 describes a component for a motor vehicle, in particular transverse member for arrangement between the A-pillars of a motor vehicle, with an essentially tube-like main body, within which there is at least one duct provided. In order to provide an improved lightweight component which can be produced more easily, with fewer operations, and therefore at lower cost, and into which a duct can be integrated in advantageous manner, DE 100 64 522 A1 proposes that the main body have an internal lining of plastic to form duct walls composed of plastic. The said component can be used as instrument-panel support in a motor vehicle. Holders, such as a steering-column holder, are attached to the main body, and these holders are likewise preferably composed of metal. According to DE 100 64 522 A1, the holders can be surrounded by plastic, thus increasing their stiffness, eliminating rattle, and providing edge protection.
DE 100 22 360 A1 describes a composite component composed of two or more profiles and describes a process for production of this component, where a free end of at least one profile is adjacent to the second profile or protrudes into the second profile, characterized in that reinforcement elements have been attached in the region of the junction site of the profiles and form an interlock bond with the profiles, and that the profiles have been bonded to one another via thermoplastic that has been applied by a moulding or shrinkage process in the region of the junction site.
DE 103 60 045 A1 describes a hybrid transverse member for a vehicle with a metallic cross strut with a section which runs in the form of an open channel in the main direction of the hybrid transverse member, and the longitudinal edges of which have been bonded, in one section, to a structural element composed of plastic, preferably via an adhesive joint.
There is also a hybrid transverse member proposed for a vehicle and having a metallic transverse strut which comprises a section running in the main direction of the hybrid transverse member in the form of an open channel, and with a steering-column link attached centrally externally thereto, and also with an auxiliary strut arranged within the profile of the metallic transverse strut in the region of the steering-column link.
DE 10 2004 032 951A1 relates to a component, in particular a transverse member for arrangement between A-columns of a motor vehicle, with a main body which is designed in essence as hollow profile and which internally has a guide duct, and which has at least one link with which it is possible to integrate an add-on part subsequently in a processing step.
DE 10 2008 012 066 U1 reveals a transverse-member module which is intended to receive the instrument panel of a motor vehicle, comprising an at least partially plastics-surrounded metal tube, and a simply moulded sheet-metal profile functioning as steering-column retainer and designed and placed in such a way that, in the composite with moulded-on plastic, it firstly gives a stiff connection between steering column and front wall and secondly has firm connection to the metal tube by way of a structure consisting entirely of plastic.
A feature common to all of the solutions described in the prior art for the connection of steering-column retainer and transverse member is that they either comprise only holders composed of metal or composed of plastic which do not receive a steering console until an additional operation is carried out, or, to the extent that the moulding-on of the steering console is simultaneous with that of the plastic for the ribbing, this is composed solely of plastic, as is the case in DE 200 08 201U1.
The consequence of the two-part design is increased operating cost, and the consequence of the solution entirely composed of plastics according to DE 200 08 201U1 is lack of stability. The solutions described in the prior art moreover exhibit disadvantageous vibration behaviour, perceptibly extending as far as the steering wheel. Although DE 10 2005 004 605 A1 indicates that the proposed hybrid design of the transverse-member module reduces oscillating mass, but provides a transverse member with relatively high intrinsic frequency, giving a transverse-member module with a high level of vibration comfort, it has been found that in modified vehicle configurations this mitigation of vibration behaviour solely of the transverse member is insufficient, and in fact that unpleasant vibration behaviour extends as far as the steering wheel.
Another disadvantage of the transverse-member motor-vehicle modules described in the prior art is the fact that when there is a need to perform various functions, functional elements using exactly the same type of plastic are moulded on to the transverse-member module. By way of example, in DE 100 64 522 A1 exactly the same plastic serves for moulding air-outflow connections, retainers and link elements, or a plastics shell, and also to ensure link thereof to the tubular transverse member. Here, exactly the same plastic is assuming not only functions subject to load but also functions which have no or only slight exposure to load during the operation of a motor vehicle.
One way of taking account of this situation is to use multicomponent technology. The various types of multicomponent technology are                Bi-injection moulding, i.e. simultaneous injection of two or more components into the same cavity.        Core-back processes, i.e. the injection of two or more components in sequence, where the cavity for the 2nd component is made available by withdrawing a sliding barrier.        Transfer processes, i.e. using a preform which is transferred to a 2nd cavity or 2nd machine before the 2nd component is injected.        Sandwich processes, i.e. construction of layers using outer skin/core, where the layers are injected in succession.        